Influence of Er:YAG laser on microtensile and in enamel/resin interface

Objective: The objective of this study was to evaluate in vitro the influence of Er:YAG laser energy to cavity preparation on microtensile bond strength and in the morphology of interface, using a self-etching adhesive system (Tyrian SPE/One-Step Plus). Methods: For microtensile bond strength 24 teeth were selected and flattened in buccal surfaces without dentine exposure. In the control group (n=8) was utilized bur carbide in a high-speed. In the experimental group (n=16) was utilized laser with energies: 250 e 300mJ. The surfaces were restored with composite resin (Z250). After 24 hours at 37°C, the specimens were sectioned in sticks with area of ±0.8mm2 and placed in a universal testing machine (0.5 mm/min). For morphological analysis were prepared 9 teeth (n=3 - control, n=6 - experimental). The specimens were prepared for SEM. Results: The results were analyzed by KrusKal-Wallis test. Means in MPa were: 21.39 (±5.91)-control, 11.85 (±5.30)-250mJ and 9.33 (±6.65)-300mJ. The control group had the highest mean and was statistically different from the groups with laser (p<0.01). The morphological analysis revealed the formation of slender adhesive interface for control group. The experimental group with energy of 300mJ showed an irregular adhesive interface with amorphous enamel and areas of fusion. The energy of 250mJ promoted the more regular surface with good formation of adhesive interface. Conclusions: It was concluded that the laser influenced in adhesion and in the morphology, presenting smaller bond strength that the conventional treatment and a more irregular adhesive interface. Grant sponsor: CAPES.